1. Field of the Invention
The present invention relates to a sorting apparatus and more particularly to a sorting apparatus which is used to automatically sort recorded sheets.
2. Description of the Prior Art
In a prior art sorting apparatus of the type described above, a plurality of trays in which printed and then sorted sheets are stored are disposed vertically along a sheet discharge unit fixed relative to the trays. In like manner, a sheet feeding unit which receives sheets from a host system such as a copying machine is also fixed. The sheets which are received from a sheet discharge portion of the host system are transported by a transport member to the sheet discharge unit from which the sheets are directed to the respective trays.
That is, in the sorting apparatus of the type described, in order to align the inlet of the tray into which the sheets are introduced with the fixed discharge unit whenever the sheets are fed, a plurality of trays must be sequentially moved vertically. To this end, in response to the sheet feeding operation, a plurality of trays must be, for example, moved or shifted downward or upward by one stage by a moving or shifting member.
However, when the sheet feeding unit, the sheet discharge unit and the transport passage interposed therebetween are fixed, it is necessary to provide a sufficient space which can accommodate a predetermined number of trays both above and below the sheet discharge unit, so that a plurality of trays can be moved both upward and downward. As a result, the whole height of the sorting apparatus is increased, resulting in that the sorting apparatus is large in size.
Furthermore, the position of the sheet feeding unit which receives the sheets from the host system is not variable, so that one sorting apparatus cannot be used in common to various types of host systems. In addition, in the prior art sorting apparatus in which the trays are permanently or semipermanently fixed, it is required that the sheet transport member and the sheet sorting member must be co-operative with each other so that a sheet is transported into a desired tray from the sheet feeding unit. This causes that the sorting apparatus becomes very complicated in mechanism.
In order to overcome the above and other problems encountered in the prior art sorting apparatus, there has been proposed a sorting apparatus of the type disclosed in Japanese Laid-open Patent Application Publication No. 59-215895, laid-open on Dec. 5, 1984. In this apparatus, a horizontal shaft carries at its both ends cams (Geneva wheels), each of which is in the form of a disc and has slots along the periphery. The horizontal shafts has its ends fitted into vertical guide grooves in such a way that the horizontal shaft is vertically slidable. The upper and lower peripheral surfaces of the Geneva wheel support tray pins extended from both ends of the tray, whereby a tray inlet is defined between them. Upon rotation of the horizontal shaft and the Geneva wheels, the tray pins are fitted into the slots so that the tray itself is moved upward or downward and consequently the tray inlet is defined at a shifted position.
FIGS. 1 and 2 show the sorting apparatus of the type described above. Reference numeral 1 designates a Geneva wheel in the form of a disc cam which is attached to a rotating shaft 2 at its substantially end position. The Geneva wheel 1 has slot 1A into which a tray pin 3A is slidably fitted. The rotating shaft 2 is supported through bushings 24 by opposed frame walls 4 in such a manner that the rotating shaft 2 can be vertically moved along guide grooves 5 formed in the frame walls 4.
As shown in FIG. 2, the rotating shaft 2 has a sprocket wheel 6 and is driven in a direction selected by a reversible motor 8 through a belt 7 drivingly intercoupling the motor 8 to the sprocket wheel 6. A hollow rotating shaft 9 into which the rotating shaft 2 is inserted is loosely and coaxially engaged with the rotating shaft 2 and is driven by a motor 10 through a belt 11. Upon rotation of the hollow rotating shaft 9, a sheet is discharged from a tray inlet 17 to a tray 13A disposed below the tray inlet 17 by sheet discharge rollers 12 carried by the hollow rotating shaft 9. Reference numeral 14 denotes a groove into which the tray pins 3A are vertically slidably fitted. Reference numeral 15 is a transport member which is a part of a recording apparatus such as a copying machine. The stacked trays 13 are supported by a tray stand 25.
In the sorting apparatus of the above-described construction, when the tray inlet holding member, that is, the Geneva wheel 1 is rotated, for instance, in the clockwise direction from the position as shown in FIG. 1, then the tray 13 which has been supported by the upper half of the periphery of the Geneva wheel 1 drops into the slot 1A, so that this tray 13 can be lowered by the tray pin 3A to the position where the tray 13 is stacked on the second tray 13 immediately below the first mentioned tray 13, whereby the tray inlet 17 is defined upward by one stage.
When the Geneva wheel 1 is rotated in the counterclockwise direction from the position as shown in FIG. 1, the pin 3A which has been in contact with the lower half of the outer periphery of the Geneva wheel 1 engages with the slot 1A, so that the tray 13 is lifted to the position where the first mentioned tray 13 lifts the second tray 13 immediately above the first mentioned tray 13.
In this manner, as shown in FIG. 3, the lower trays 13 are sequentially moved upward, while the Geneva wheel 1 is lowered accordingly, so that sheet guide members 11A and 11B are inclined downwardly and consequently the sheet 23 is directed into the tray inlet 17 by a discharge roller 12 as shown in FIG. 3.
However, when it is desired to move a desired tray 13 in the sorting apparatus of the type described above, there arises the problem that, as shown in FIG. 3, the Geneva wheel 1 must bear the whole weight of the trays positioned above the Geneva wheel 1.
That is, while the stacked trays 13 are supported by the tray stand 25, the leading ends of the stacked trays 13 are supported through a support (not shown) in such a way that the leading ends are made into contact with each other. On the other hand, on the side of the tray inlet 17, the Geneva wheel 1 serves as cantilever and supports the whole weight of the trays disposed above the Geneva wheel 1.
The load applied to the Geneva wheel 1 is increased as the Geneva wheel 1 is positioned lower; that is, when the inlet 17 is defined between the lower trays. Especially, when many recorded and sorted sheets are stacked on each of the trays 13, a heavier load is exerted to the Geneva wheel 1.
When the motor 8 must drives to rotate the Geneva wheel 1 so that the pin 3A which has been in contact with the lower half of the periphery of the Geneva wheel 1 is caused to engage with the slot 1A, thereby moving it upward the work is required for driving the Geneva wheel 1 against the load of the stacked trays, in addition to the work done for moving one tray 13 itself upward in the manner described above. As a result, the torque of the motor 8 must be increased. That is, a power supply, the motor 8 and other mechanisms are so designed and constructed to produce such a great torque.
Recently, it is desired that the sheets are processed at a high speed and that many sheets are stored in one sorting apparatus. As a result, the cost is increased. In addition, whenever a new type of sorting apparatus is designed, the capacity of the motor 8 and the mechanism associated with the motor 8 must be determined based upon the above described conditions. This results in the increase of design cost.